#include<iostream>
#include<unordered_map>
using namespace std;

int main()
{
    unordered_map<string,char> map;
    //map.insert({"apple",'a'});
    //map["apple"]='a';
    //map["apple"]='a';
    //map.insert({"banana",b});
    map["banana"]='b';
    //返回值为bool，看健是否出现过
    int a=map.count("apple");
    cout<<a<<endl;
    string s="hello world aaa bbb";
    const char* cs=s.c_str();
    cout<<cs<<endl;
    cout<<cs[0]<<endl;
    cout<<s[0]<<endl;
    cout<<s.insert(5,"ysy")<<endl;
    cout<<s.empty()<<endl;;
    cout<<s.length();
    return 0;
}